Piston expander



Patented Sept. 17, 1935 UNITED STATES.

PATENT oFFieE 2,014,645 PISTON EXPANDER. Mathew J. Burkel, Aurora, Ill. Application October 16, 1934, Serial No. 748,497

4 Claims.

This invention relates to that type of pistons for high speed internal combustion and like engines which are provided with a depending circular extension or skirt, formed with longitudinal slots in order to becapable of limited expansion under the influence of a resilient expander secured against longitudinal displacement in the cavity of the piston and adapted to resiliently hold the piston skirt in close contact with the inner wall of the engine cylinder and prevent the usual piston slap as well as undue leakage of oil past the piston rings of the above mentioned type of engines. And this improvement has for its object:-

To provide a structural formation of a resilient expander for enginepistcns of the slotted skirt type of a simple, durable and efiective formation and which due to such formation is capable of maintaining itself against longitudinal displacement in actual use, without other means of attachment, all as will hereinafter more fully appear.

In the accompanying drawing:

Fig. l is a longitudinal section on line l--l Fig. 3, of an ordinary form of skirted piston with resilient skirt expander of this improvement in place therein.

Fig. 2 is a similar section on line 2-2 Fig. 3, and taken on a plane .at right angles to the plane on which Fig. l is taken.

Fig. 3 is an inverted plan of the piston showing the expander in place.

Fig. 4 is a detail perspective view of the expander.

Like reference numerals indicate like parts in the difierent views.

The construction of pistons to which this invention is effectively applicable is of a generally used formation, and comprises an upper closed head I; a depending open bottom skirt portion 2 formed with transverse slots 3 adjacent to the head I and a longitudinal slot 4 extending from the lower end of the skirt 2 and opening into the transverse slots 3 aforesaid, and with piston pin bosses or hubs 5 in diametrically opposed relation in the circular wall of said skirt, as shown in the.

drawing.

As shown in the drawing, the resilient expander of this improvement is formed from a single piece of resilient rod metal, preferably of a, rounded shape in cross section, and in detail comprises integrally connected members as follows:

An upper horizontal crown portion 6 of an inwardly curved form so as to provide bearing shoulders 6' in spaced relation and adapted to bear against the inner face of the piston skirt 2 at a point below the transverse slots 3, and as so formed said crown portion 6 is adapted to exert an outward resilient expanding pressure on the portion of said skirt 2 adjacent to the closed piston 5 head I. r

The respective ends of the horizontal crown portion 6 are connected by bends with downwardly and laterally extending side portions 1 which in turn have curved connections with 10 downwardly and laterally extending side portions 8 with said curved connections forming bearing humps 9 for the purpose hereinafter described.

The lower ends of the last mentioned side portions 8 are in turn connected by bends with a 15 pair of outwardly curved horizontal portions it which are so arranged as to cross each other, as illustrated in Figs. 1 and 2, and have bearing contact on opposite sides of the longitudinal slot 4 of the piston skirt, so that the free ends of 20 each respective portion l0 passing over the slot 4 will have resilient bearing on the portion of the piston skirt remote from its main portion.

With the expander constructed as above described, the same is applied in proper posi- 25 tion within the piston skirt by being pushed by hand into place with the humps 9 formed at the intersection of the downwardly and laterally extending portions 1 and 8 have bearing against the perimeter of the piston pin bosses or hubs 5 30 at points above a plane cutting the horizontal axis of said piston pin receiving bosses, as shown in Fig.

2. With this arrangement the bearing contact of the humps 9 against the upper portion of the perimeter of the bosses or hubs 5 constitute a sub- 35 stantial means for maintaining the expander in proper place against a tendency to longitudinal displacement in actual use and without any additional holding provisions.

The crossing of the lower horizontal portions 40 H] of the expander is a material feature of this invention in that it has been found after extended experiments that the spanning of the longitudinal slot 4 of the piston skirt attains a very effective action during long continued use. 7 45 Having thus fully described my invention what I claim as new, is:-

1. In combination with a piston having a longitudinally split skirt provided with piston pin bosses in opposed relation, an expander formed of 50 a rod of resilient metal and comprising an upper horizontal portion, a pair of downwardly extending portions connected at their upper ends to the ends of said horizontal portion and provided with means for securing the expander in 5 place in the interior of the piston skirt, and a pair of lower horizontal portions connected at one end to said downwardly extending portions with their free ends overlapping the longitudinal slit of the piston skirt.

2. In combination with a piston having a longitudinally split skirt provided with piston pin bosses in opposed relation, an expander formed of a rod of resilient metal, and comprising an upper horizontal portion, a pair of downwardly and laterally extending portions connected at their upper ends to said horizontal portion and formed with bearing humps at their mid-length adapted for bearing contact on the upper perimeter of the bosses for the piston pin, and lower horizontal portions connected to said downwardly extending portions with their respective free ends overlapping the lower end of the longitudinal split of the skirt of the piston.

3. In combination with a piston having a longitudinally and transversely slitted skirt provided with piston pin bosses in opposed relation, an expander formed of a rod of resilient metal and comprising an upper horizontal portion of an inwardly curved form providing near its respective ends bearing points adapted for bearing on the transversely slitted portion of the piston skirt,

a pair of downwardly extending portions connected at their upper ends to the ends of said horizontal portion and provided with means for securing the expander in place in the interior of the piston skirt, and a pair of lower horizontal portions connected at one end to said downwardly extending portions with their free ends overlapping the longitudinal slit of the piston skirt.

4. In combination with a piston having a longitudinally and transversely slitted skirt'provided with piston pin bosses in opposed relation, an expander formed of a rod of resilient metal and 7 comprising an upper horizontal portion of an in- MATHEW J. BURKEL. 

